During a 2012 outbreak of pertussis in Wisconsin, inoculation of adolescents with Tdap vaccinations showed dwindling immunity with time, according to recent findings.

Although the Boostrix (GlaxoSmithKline) Tdap vaccine demonstrated greater efficacy than Adacel (Sanofi-Pasteur), these findings may not be generalizable to other adolescents who received different DTaP vaccines during childhood, the researchers wrote.

The researchers utilized data from the population-based Wisconsin Immunization Registry to track the effectiveness of Tdap by brand and year of receipt. The registry is a statewide immunization information system that chronicles and monitors immunization histories for all residents of Wisconsin.

The researchers found that, overall, Tdap efficacy after time of receipt declined as follows:

  • 75.3% for vaccines received in 2012;
  • 68.2% for vaccines received during 2011;
  • 34.5% for vaccines received in 2010; and
  • 11.9% for vaccines received during 2008-2009.